JP4134740B2

JP4134740B2 - Lens adjustment method and apparatus

Info

Publication number: JP4134740B2
Application number: JP2003021827A
Authority: JP
Inventors: 雅弘桑原; 正弥伊藤; 耕基中林
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2003-01-30
Filing date: 2003-01-30
Publication date: 2008-08-20
Anticipated expiration: 2023-01-30
Also published as: JP2004233638A

Description

【０００１】
【発明の属する技術分野】
本発明は、レンズの組立調整を行うレンズ調整方法及びその装置に関するものである。
【０００２】
【従来の技術】
従来のレンズ組立方法及び装置としては、例えば、特許文献１に記載された発明が知られている。
【０００３】
図１４は従来の技術におけるレンズ調整システムを示す。この図に示すレンズ調整システムにおいて、光源５１から出射した光は、コリメートレンズ５２によって平行光に変換された後、鏡筒に固定されたレンズ５３，被調整レンズ５４に入射する。レンズ５４を通過した光は、これらレンズ５３、５４によって透過型回折格子５５上に集光される。回折格子５５を透過した光は、広がりながらコリメートレンズ５６に入射する。コリメートレンズ５６を透過した光は平行光となり、更に集光レンズ５７により集光され、該集光レンズ５７の瞳面が受像素子（撮像素子）５８に受像される。
【０００４】
このシステムにおいて、光は透過型回折格子５５により回折を起こす。したがって、回折格子５５を透過した光は、図１５に示すように、０次、±１次、±２次、・・の回折光となる。このとき、回折格子５５に角度（回折格子に対する光の入射絞り角）φで絞られながら入射した光は、回折角（出射角度）θの広がりを持つ±１次回折光を生じる。また、±１次光の出射角度θは、よく知られているように、回折格子ピッチｐと波長λから、式（１）で与えられる。
【０００５】
【数１】

【０００６】
したがって、角度θを適宜選択すれば、図１５に示すように、±１次回折光の輪郭が互い近づき、０次回折光と＋１次回折光、また０次回折光と−１次回折光が重なる。また、これらの重なった光は、集光レンズ５６の瞳面上で干渉縞を形成し、この干渉縞が受像素子５８に結像される。そして、処理装置５９は、受像素子５８に受像された干渉縞をもとに、集光レンズ５６の瞳面に入射した光の持つ収差を検出する。
【０００７】
また、精度よく各収差を検出するには、一般に知られているフリンジスキャン法が好適に用いられる。具体的に、例えばピエゾ素子を利用したピエゾ型移動機構（微動ステージ）６０を用いて回折格子５５を、該回折格子５５の格子方向と直交する方向又は該直交する成分を含む方向に移動すると、干渉領域における光強度が正弦波状に変化する。この場合、光の強度むらに影響されることなく、位相差に基づいて高い精度の収差検出が行える。そして、処理装置５９は、回折格子５５をピエゾ型移動機構６０によって移動（微動）し、干渉領域内に設定されたある基準線上の複数の点で光強度の位相を求め、それらの位相差をもとに対応する収差を求める。
【０００８】
以上のようにして処理装置５９で検出された各収差は制御装置６１に送られる。そして、制御装置６１は、各収差をもとに、移動機構（調整装置）６２を駆動し、レンズ保持具６３、及び保持されたレンズ５４を位置調整する。
【０００９】
【特許文献１】
特開２００２−２０２４５０号公報
【００１０】
【発明が解決しようとする課題】
しかしながら、前述する調整方法は、ＮＡが大きい光ディスクのピックアップ対物レンズ等に用いられているが、カメラレンズで用いられるＮＡが小さいレンズの場合、被調整レンズ５４のディセンタに対する収差の変動量が小さいため、高精度な調整を行うことが難しい。また、光ディスクのピックアップでは、軸上の光を用いてデータの読み書きを行うが、カメラでは軸外の光も用いるため、この調整方法では軸外の高画角の光に対して特性を保障することも難しい。更に、レンズ５４のディセンタとチルトをあわせた値を収差として検出するため、チルトとディセンタの切り分けが難しい。
【００１１】
そこで、本発明は、上記従来の課題を解決するものであり、ＮＡの小さいレンズに対しても高精度で調整することが可能なレンズ調整方法及びその装置を提供することを目的とする。
【００１２】
【課題を解決するための手段】
本発明のレンズ調整方法は、第１のレンズに対する第２のレンズの位置を調整する方法であって、（ａ）コリメートされた光を、前記第１のレンズの光軸を含む第１の平面上で前記光軸に対し＋ψ１度の傾きを持つ第１の光と、前記光軸に対し−ψ１度の傾きを持つ第２の光と、前記第１の平面と直交し且つ前記光軸を含む第２の平面上で前記光軸に対し＋ψ２度の傾きを持つ第３の光と、前記光軸に対し−ψ２度の傾きを持つ第４の光とに分岐させ、前記第１から第４の光を前記第１及び第２のレンズでそれぞれ集光させる工程と、（ｂ）前記集光された４光をそれぞれ回折格子で回折して干渉させる工程と、（ｃ）前記４つの干渉した光から形成された４つの干渉像を受像する工程と、（ｄ）前記受像した４つの干渉像からそれぞれ前記第２のレンズのディセンタに対して感度を持つ収差を検出する工程と、（ｅ）前記光軸を法線とする平面上で前記第２のレンズの位置を変化させた後に前記第２のレンズのディセンタに対して感度を持つ収差を検出する工程と、（ｆ）前記検出結果から前記第２のレンズの位置変化に対する収差変化の関係を求める工程と、（ｇ）前記求めた関係から前記第１の光に対する収差量と前記第２の光に対する収差量が等しくなる位置及び前記第３の光に対する収差量と前記第４の光に対する収差量が等しくなる位置を算出する工程と、（ｈ）前記算出した位置に前記第２のレンズを調整する工程と、を有することを特徴とする。
【００１３】
【発明の実施の形態】
（第１の実施の形態）
図１は本発明の第１の実施の形態におけるレンズ調整システムを示すものである。図１において、１は鏡筒に固定された第１のレンズであり、第１のレンズ１の光軸を、レンズ調整システムの光軸（Ｚ軸）とする。
【００１４】
このレンズ調整システムにおいて、コヒーレントな平行光を発する光源２から出射した光は、光分岐装置３によって光軸を含む第１の平面上（ＸＺ平面）で光軸に対し＋ψ１度の傾きを持つ第１の光と光軸に対し−ψ１度の傾きを持つ第２の光、光軸を含み前記第１の平面と直交する第２の平面上（ＹＺ平面）で光軸に対し＋ψ２度の傾きを持つ第３の光と光軸に対し−ψ２度の傾きを持つ第４の光の合わせて４光に分岐される。光分岐装置３は、入射した光を３枚のハーフミラーで４分岐し、更に分岐した光の出射角を全反射ミラーで設定する構成になっている。
【００１５】
光分岐装置３で４分岐された光は、前記第１のレンズ１、及び被調整レンズである第２のレンズ４に入射する。第１のレンズ１及び第２のレンズ４を通過した４光は、これらレンズによってそれぞれ回折格子５上に集光される。
【００１６】
図２は、回折格子５の形状の一例を示すもので、回折格子５の中心Ａにおける法線が光軸とほぼ一致するように位置している。回折格子５を透過した光は、回折を起こす。回折格子に対する光の集光角φ及び波長λに対し、回折格子ピッチｐを適当に選択することにより０次回折光と＋１次回折光、また０次回折光と−１次回折光が重なる。
【００１７】
これらの重なった光は、その中心がほぼ第１の平面上に位置する第１の干渉像観察系６と第２の干渉像観察系７及びその中心がほぼ第２の平面上に位置する第３の干渉像観察系８と第２の干渉像観察系９により観察される。
【００１８】
図３は、これら干渉像観察系の構成を示すもので、１０は対物レンズ、１１は結像レンズ、１２はＣＣＤカメラである。回折格子５を透過し回折された光は、対物レンズ１０の瞳面上で干渉縞を形成し、この干渉縞が結像レンズ１１によりＣＣＤカメラ１２の受像素子上に結像される。そして、処理装置１３は、受像された干渉縞をもとに収差を検出する。なお検出する収差は、第２のレンズ４のディセンタに対して充分な感度を有する収差のなかの一つの収差、例えば、非点収差あるいはコマ収差である。
【００１９】
収差の検出には一般に知られているフリンジスキャン法が好適に用いられる。ピエゾ素子を利用したピエゾ型移動機構（微動ステージ）１４を用いて回折格子５を、該回折格子５の格子方向と直交する方向又は該直交する成分を含む方向に、例えば、図２に示す回折格子ではＢまたはＣ方向に移動すると、干渉領域における光強度が正弦波状に変化する。この場合、光の強度むらに影響されることなく、位相差に基づいて高い精度の収差検出が行なえる。そして、処理装置１３は、回折格子５をピエゾ型移動機構１４によって移動（微動）し、干渉領域内に設定されたある基準線上の複数の点で光強度の位相を求め、それらの位相差をもとに対応する収差を求める。
【００２０】
次に、光軸に対して第２のレンズ４の位置を調整する方法を図４に示す工程フローを用いて説明する。
【００２１】
まず、鏡筒に固定された第１のレンズ１を鏡筒保持具１５で固定する。次に、第２のレンズ４をレンズ保持具１６で保持する。
【００２２】
この第２のレンズ４を保持した位置、第１の測定点において光源２を発光させて、処理装置１３により収差を検出する。そして、第２のレンズ４を調整装置１７によって、直線Ｙ＝Ｘに沿って所定量動かして第２の測定点に移動させ、再び処理装置１３により収差を検出する。ここで第２のレンズ４をＸ方向に動かした場合の第１の干渉像観察系６と第２の干渉像観察系７で測定した２つの収差量の変化を図５に、第３の干渉像観察系８と第４の干渉像観察系９で測定した２つの収差量の変化を図６に示す。
【００２３】
第２のレンズ４のＸ方向の移動に対し、ＹＺ平面上の第３の干渉像観察系８と第４の干渉像観察系９による収差量はほとんど変化しないのに対し、ＸＺ平面上の第１の干渉像観察系６と第２の干渉像観察系７による収差のうちの一方は増加し、他方は減少する。その交点は２つの収差が等しくなる収差対称位置であり、Ｘ方向について第１のレンズ１の光軸と第２のレンズ４の光軸が一致している。
【００２４】
同様に、第２のレンズ４のＹ方向の移動に対しては、ＹＺ平面上の第３の干渉像観察系８と第４の干渉像観察系９による収差量は図５のように変動し、その収差対称位置が求まるのに対し、ＸＺ平面上の第１の干渉像観察系６と第２の干渉像観察系７による収差量は、ほとんど変化しない。
【００２５】
従って、第２のレンズ４を調整装置１７によって、直線Ｙ＝Ｘに沿って動かし収差を測定すると、Ｘ、Ｙ方向について図５のようなグラフが描け、それぞれ収差対称位置となる交点を求めることができる。通常、カメラで用いられるレンズあるいはレンズ群の場合、画角の大きい光に対するＭＴＦの劣化が大きく、特性に影響を与える。本調整システムでは、光が光軸に対してψ１度あるいはψ２度の角度を有しているため、軸上の光（入射角０度）に対する場合よりも収差変化量が大きく、高精度で交点を検出できる。
【００２６】
あるデジタルカメラで用いられているレンズにおいて、第２のレンズ４を光軸を法線とする平面上で光軸からディセンタさせたときの十字方向非点収差の変化の計算結果を、軸上光（入射角０度）の場合を図７に、軸外光（入射角１２度）の場合を図８に示す。第２のレンズ４のディセンタ１μｍに対しての収差変化量は、軸上光が０．１ｍλ以下であるのに対し、軸外光では５．５ｍλであり、軸外光を用いることにより、より高精度な位置検出ができることがわかる。
【００２７】
この交点位置は制御装置１８に送られる。そして、制御装置１８はこの位置をもとに調整装置１７を駆動し、第２のレンズ４をＸＹ平面上で移動させることにより、レンズ４の位置調整を行う。
【００２８】
なお、収差対称位置の算出のための収差測定を、第２のレンズ４を移動させ直線Ｙ＝Ｘ上の２点で行ったが、Ｙ＝Ｘ上の２点以上の複数点で行うことにより精度が向上することは言うまでもない。
【００２９】
以上説明したように、第１の実施の形態によれば、第１のレンズに対し、第２のレンズを調整するため、第１のレンズの光軸を基準の光軸として、（ａ）レーザ光を、レーザ光線まわりに回転する水晶板に入射する工程と、（ｂ）上記入射した光を水晶板で横変位を受けない第１の光と横変位をうける第２の光に分岐する工程と、（ｃ）上記分岐した２光をハーフミラーで反射し第２のレンズに入射する工程と、（ｄ）上記入射光を第２のレンズ表面で反射させる工程と、（ｅ）上記反射光をＰＢＳで分岐する工程と、（ｆ）上記分岐した光をそれぞれシリンドリカルレンズでラインセンサのライン上に集光する工程と、（ｇ）上記ラインセンサで上記第２のレンズ反射光の位置を検出する工程と、（ｈ）上記検出位置から、第２のレンズのディセンタ量とチルト量を算出する工程と、（ｇ）上記算出量に基づいて第２のレンズを調整する工程とを有する組立調整を行うことにより、ＮＡの小さいレンズに対しても、ディセンタ量を高精度で検出し、調整を行うことができる。
【００３０】
（第２の実施の形態）
図９は本発明の第２の実施の形態における組レンズ調整システムを示すもので、図９において図１と同一の機能を持つものは動作も同様であり、同一の符号を付して説明を省略する。
【００３１】
１９はディセンタ（ＸＹ）調整とチルト（θｘθｙ）調整機能のついた調整装置であり、制御装置１６の指令に基づいて駆動する。２０は干渉縞から２種類の収差を検出する処理装置である。
【００３２】
次に、本実施の形態によるレンズ調整方法について説明する。第１の実施の形態とほぼ同じフローであるが、検出する収差の数と第２のレンズ４のディセンタ量に加えてチルト量を算出・調整する点が異なっている。
【００３３】
本実施の形態では、第２のレンズ４のディセンタに対して十分な感度を有し、かつチルトに対しての感度に差がある２つの収差、例えば、非点収差とコマ収差を処理装置２０において検出する。第２のレンズ４を直線Ｙ＝Ｘに沿って所定量動かして、第１の測定点及び第２の測定点において前記２つの収差を検出するとＸ、Ｙ方向について、図１０のようなグラフが描ける。第２のレンズ４にチルトがある場合、非点収差に比べコマ収差の方がチルトに対する感度が大きいため、非点収差とコマ収差でグラフの交点（収差対称位置）にずれが生じる。
【００３４】
図１１は、第２のレンズ４のチルト量に対する非点収差とコマ収差の交点位置及びそのずれ量を示したものである。非点収差とコマ収差の交点位置ずれ量は第２のレンズ４のチルト量に対して決まった値になるため、このずれ量を測定することにより第２のレンズ４のチルト量を算出することができる。また、同時にチルト量が０の場合の交点位置（＝光軸）も算出することができる。このチルト量及び中心位置をもとに、制御装置１８は、調整装置１９を駆動し、第２のレンズ４のディセンタ及びチルト調整を行う。
【００３５】
以上説明したように、第１の実施の形態ではレンズのディセンタ量のみを検出・調整するのに対し、第２の実施の形態によれば、レンズのディセンタに対して感度を有し、かつチルトに対する感度が異なる２つの収差、例えば非点収差とコマ収差について測定を行うことにより、レンズのディセンタ量とチルト量を独立に高精度で検出し、調整することができる。
【００３６】
（第３の実施の形態）
図１２は本発明の第３の実施の形態におけるレンズ調整システムを示すものである。
【００３７】
図１２において、３１は鏡筒、３２は鏡筒に固定された第１のレンズであり、第１のレンズ３２の光軸を、レンズ調整システムの光軸（Ｚ軸）とする。
【００３８】
このレンズ調整システムにおいて、円偏光の光を発する光源３３から出射した光は、その光学軸が前記光線を含む平面上で前記光線と４５度の角度をなすように配置された水晶板３４により横変位を受けない第１の光と横変位ｄを受ける第２の光に分岐される。分岐した２光はハーフミラー３５により反射され被調整レンズである第２のレンズ３６に入射する。第２のレンズ３６に入射する第１の光が光軸と一致するように、光源３３、水晶板３４及びハーフミラー３５は位置している。
【００３９】
第２のレンズ３６の表面で反射した光は、ハーフミラー３５を透過し、ＰＢＳ３７に入射する。ＰＢＳ３７は、その反射面がＹ軸と平行かつ光軸（Ｚ軸）と４５°をなすように位置しており、偏光方向がＸ軸と平行な成分は透過し、Ｙ軸と平行な成分は反射する。ＰＢＳ３７の透過光は光軸を中心とし、ライン方向がＹ軸と平行な第１のラインセンサ３８で検出される。
【００４０】
ＰＢＳ３７の反射光は、光軸上の光がＰＢＳ３７で反射されたときの光線を中心とし、ライン方向がＺ軸と平行な第２のラインセンサ３９で検出される。ＰＢＳ３７と第１のラインセンサ３８の間には、Ｘ軸方向に拡がった光を集光する第１のシリンドリカルレンズ４０があり、Ｘ軸方向にずれたＰＢＳ３７透過光を第１のラインセンサ３８上に集光させる。同様に、ＰＢＳ３７と第２のラインセンサ３９の間には、Ｚ軸方向に拡がった光を集光する第２のシリンドリカルレンズ４１があり、Ｚ軸方向にずれたＰＢＳ３７反射光を第２のラインセンサ３９上に集光させる。本実施の形態では、光の位置の検出を、２つの光を分離して別々のラインセンサで行うため、高速に行うことができる。
【００４１】
次に、光軸に対して第２のレンズ３６の位置を調整する方法を図１３に示す工程フローを用いて説明する。
【００４２】
まず、鏡筒に固定された第１のレンズ３２を鏡筒保持具４２で固定する。次に、第２のレンズ３６をレンズ保持具４３で保持する。
【００４３】
ここで光源３３を発光させ、水晶板３４を回転機構４４より光線まわりに回転させると、第２の光は第１の光を中心として回転する。従って第２のレンズ３６には、光軸上の光（第１の光）と光軸まわりに回転する光（第２の光）の２光が入射する。第２のレンズ３６にディセンタとチルトが無い場合、第２のレンズ３６からの反射光の位置は、第１の光の反射光である光軸上の１点と第２の光の反射光である光軸を中心とするある半径を持つ円となる。
【００４４】
第２のレンズ３６にディセンタとチルトがある場合は、第１の光の反射点位置Ｃ１が光軸からずれ、第２の光の反射光の軌跡が楕円となるとともにその中心Ｃ２も光軸からずれる。第１のラインセンサ３８でＰＢＳ３７の透過光を観測することにより、Ｃ１のＹ座標及び第２の光が描く楕円のＹ軸方向の楕円径、軸方向を検出し、第２のラインセンサ３９でＰＢＳ３７の反射光を観測することにより、Ｃ１のＸ座標及び第２の光が描く楕円のＸ軸方向の楕円径及び軸方向を検出する。
【００４５】
検出したＣ１、Ｃ２、及び楕円形状の値は、処理装置４５に送られ、第２のレンズ３６の表面形状から得られる計算値と比較することにより、第２のレンズ３６のチルト量とディセンタ量を算出することができる。算出結果は制御装置４６に送られ、算出結果に基づき調整装置４７を駆動して第２のレンズ３６の調整を行う。
【００４６】
なお、ＰＢＳ２７と第１の第１のシリンドリカルレンズ４０及び第２のシリンドリカルレンズ４１の間にそれぞれのシリンドリカルレンズが集光する方向と垂直方向に集光するシリンドリカルレンズを挿入することにより、ラインセンサ上の光が集光され、位置検出制度が向上することは言うまでもない。
【００４７】
以上説明したように、第３の実施の形態によれば、回転する水晶板で分岐した２つの光をレンズに照射し、その反射光位置を２つのラインセンサで観測し、解析することにより、レンズのチルト・ディセンタ量を独立で高速で検出し、調整を行うことができる。
【００４８】
以上説明したように、本発明によれば、第１のレンズに対する第２のレンズの位置を調整する方法であって（ａ）コリメートされた光を、前記第１のレンズの光軸を含む第１の平面上で前記光軸に対し＋ψ１度の傾きを持つ第１の光と、前記光軸に対し−ψ１度の傾きを持つ第２の光と、前記第１の平面と直交し且つ前記光軸を含む第２の平面上で前記光軸に対し＋ψ２度の傾きを持つ第３の光と、前記光軸に対し−ψ２度の傾きを持つ第４の光とに分岐させ、前記第１から第４の光を前記第１及び第２のレンズでそれぞれ集光させる工程と、（ｂ）前記集光された４光をそれぞれ回折格子で回折して干渉させる工程と、（ｃ）前記４つの干渉した光から形成された４つの干渉像を受像する工程と、（ｄ）前記受像した４つの干渉像からそれぞれ前記第２のレンズのディセンタに対して感度を持つ収差を検出する工程と、（ｅ）前記光軸を法線とする平面上で前記第２のレンズの位置を変化させた後に前記第２のレンズのディセンタに対して感度を持つ収差を検出する工程と、（ｆ）前記検出結果から前記第２のレンズの位置変化に対する収差変化の関係を求める工程と、（ｇ）前記求めた関係から前記第１の光に対する収差量と前記第２の光に対する収差量が等しくなる位置及び前記第３の光に対する収差量と前記第４の光に対する収差量が等しくなる位置を算出する工程と、（ｈ）前記算出した位置に前記第２のレンズを調整する工程と、を有する組立調整を行うことにより、ＮＡの小さいレンズに対しても、ディセンタ量を高精度で検出し、調整を行うことができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態の概略図
【図２】第１の実施の形態における回折格子形状の一例を示す図
【図３】第１の実施の形態における干渉像観察系の構成を示す図
【図４】第１の実施の形態における調整フローを示す図
【図５】第１の実施の形態におけるレンズＸ方向位置変動に対するＸＺ平面上観察系の収差変動量を示す図
【図６】第１の実施の形態におけるレンズＸ方向位置変動に対するＹＺ平面上観察系の収差変動量を示す図
【図７】軸上光（入射角０度）における第２のレンズの位置変動に対する十字方向非点収差変動量の計算結果例を示す図
【図８】軸外光（入射角１２度）における第２のレンズの位置変動に対する十字方向非点収差変動量の計算結果例を示す図
【図９】本発明の第２の実施の形態の概略図
【図１０】第２の実施の形態におけるチルトがある場合のレンズ位置変動に対する収差変動量を示す図
【図１１】第２の実施の形態におけるレンズチルト量に対する非点収差とコマ収差の位置ずれ量を示す図
【図１２】本発明の第３の実施の形態の概略図
【図１３】第３の実施の形態における調整フローを示す図
【図１４】従来のレンズ調整システムの一例を示す概略図
【図１５】従来の回折格子での回折を示す図
【符号の説明】
１第１のレンズ
２光源
３光分岐装置
４第２のレンズ
５回折格子
６第１の干渉像観察系
７第２の干渉像観察系
８第３の干渉像観察系
９第４の干渉像観察系
１３１つの収差を検出する処理装置
１４移動機構
１５鏡筒保持具
１６レンズ保持具
１７平行移動機構を有する調整装置
１８制御装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens adjustment method and apparatus for assembling and adjusting a lens.
[0002]
[Prior art]
As a conventional lens assembling method and apparatus, for example, the invention described in Patent Document 1 is known.
[0003]
FIG. 14 shows a lens adjustment system in the prior art. In the lens adjustment system shown in this figure, the light emitted from the light source 51 is converted into parallel light by the collimating lens 52 and then enters the lens 53 and the adjusted lens 54 fixed to the lens barrel. The light passing through the lens 54 is collected on the transmission diffraction grating 55 by these

lenses

53 and 54. The light transmitted through the diffraction grating 55 enters the collimating lens 56 while spreading. The light transmitted through the collimating lens 56 becomes parallel light, and is further condensed by the condenser lens 57, and the pupil plane of the condenser lens 57 is received by the image receiving element (imaging element) 58.
[0004]
In this system, light is diffracted by the transmissive diffraction grating 55. Therefore, the light transmitted through the diffraction grating 55 becomes 0th-order, ± 1st-order, ± 2nd-order,... Diffracted light as shown in FIG. At this time, light incident on the diffraction grating 55 while being narrowed at an angle (incidence aperture angle of light with respect to the diffraction grating) φ generates ± first-order diffracted light having a diffraction angle (exit angle) θ. Further, as is well known, the emission angle θ of ± primary light is given by the equation (1) from the diffraction grating pitch p and the wavelength λ.
[0005]
[Expression 1]

[0006]
Accordingly, if the angle θ is appropriately selected, as shown in FIG. 15, the contours of the ± 1st order diffracted light approach each other, and the 0th order diffracted light and the + 1st order diffracted light, and the 0th order diffracted light and the −1st order diffracted light overlap. Further, these overlapping lights form interference fringes on the pupil plane of the condenser lens 56, and the interference fringes are imaged on the image receiving element 58. Then, the processing device 59 detects the aberration of the light incident on the pupil plane of the condenser lens 56 based on the interference fringes received by the image receiving element 58.
[0007]
Further, in order to detect each aberration with high accuracy, a generally known fringe scanning method is preferably used. Specifically, for example, when the diffraction grating 55 is moved in a direction orthogonal to the grating direction of the diffraction grating 55 or a direction including the orthogonal component using a piezo-type moving mechanism (fine movement stage) 60 using a piezoelectric element, The light intensity in the interference region changes in a sinusoidal shape. In this case, highly accurate aberration detection can be performed based on the phase difference without being affected by unevenness of the light intensity. Then, the processing device 59 moves (finely moves) the diffraction grating 55 by the piezo-type moving mechanism 60, obtains the phase of the light intensity at a plurality of points on a certain reference line set in the interference region, and calculates the phase difference between them. The corresponding aberration is obtained.
[0008]
Each aberration detected by the processing device 59 as described above is sent to the control device 61. Then, the control device 61 drives the movement mechanism (adjustment device) 62 based on each aberration to adjust the position of the lens holder 63 and the held lens 54.
[0009]
[Patent Document 1]
JP 2002-202450 A
[Problems to be solved by the invention]
However, the adjustment method described above is used for a pickup objective lens or the like of an optical disk having a large NA. However, in the case of a lens having a small NA used for a camera lens, the amount of variation in aberration with respect to the decenter of the adjusted lens 54 is small. It is difficult to make high-precision adjustments. In addition, optical disk pickups use on-axis light to read and write data, but cameras use off-axis light, so this adjustment method guarantees characteristics for off-axis high-angle light. It's also difficult. Furthermore, since a value obtained by combining the decenter and tilt of the lens 54 is detected as an aberration, it is difficult to separate the tilt and decenter.
[0011]
SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a lens adjustment method and apparatus capable of adjusting with high accuracy even for a lens having a small NA.
[0012]
[Means for Solving the Problems]
The lens adjustment method of the present invention is a method of adjusting the position of the second lens with respect to the first lens , wherein (a) collimated light is converted into a first plane including the optical axis of the first lens. The first light having an inclination of + ψ1 degree with respect to the optical axis, the second light having an inclination of −ψ1 degree with respect to the optical axis, and the optical axis orthogonal to the first plane and a third light having a second inclination of + .psi.2 degrees to the optical axis on the plane containing diverts into a fourth light having an inclination of -ψ2 degrees to the optical axis, first from the first A step of condensing four light beams by the first and second lenses, (b) a step of diffracting the collected four light beams by a diffraction grating, and (c) the four interference beams. Receiving four interference images formed from the received light, and (d) each of the four interference images received from the received four interference images. Detecting an aberration having sensitivity with respect to the decentering of the lens; and (e) decentering the second lens after changing the position of the second lens on a plane having the optical axis as a normal line. Detecting an aberration having sensitivity to (f), (f) obtaining a relationship of an aberration change with respect to a position change of the second lens from the detection result, and (g) the first relationship from the obtained relationship. (H) calculating the position where the aberration amount for light and the aberration amount for the second light are equal, and the position where the aberration amount for the third light and the aberration amount for the fourth light are equal; Adjusting the second lens at the position.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a lens adjustment system according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a first lens fixed to a lens barrel, and the optical axis of the first lens 1 is an optical axis (Z axis) of the lens adjustment system.
[0014]
In this lens adjustment system, the light emitted from the light source 2 that emits coherent parallel light has a first inclination (+ ψ1 degree) with respect to the optical axis on the first plane (XZ plane) including the optical axis by the optical branching device 3. 1 light and second light having an inclination of −ψ1 degree with respect to the optical axis, and an inclination of + ψ2 degrees with respect to the optical axis on the second plane including the optical axis and perpendicular to the first plane (YZ plane) The third light having λ and the fourth light having an inclination of −ψ2 degrees with respect to the optical axis are branched into four lights. The light branching device 3 has a configuration in which incident light is branched into four by three half mirrors, and the outgoing angle of the branched light is set by a total reflection mirror.
[0015]
The light branched into four by the light branching device 3 is incident on the first lens 1 and the second lens 4 which is a lens to be adjusted. The four lights that have passed through the first lens 1 and the second lens 4 are condensed on the diffraction grating 5 by these lenses, respectively.
[0016]
FIG. 2 shows an example of the shape of the diffraction grating 5, which is positioned so that the normal line at the center A of the diffraction grating 5 substantially coincides with the optical axis. The light transmitted through the diffraction grating 5 is diffracted. The 0th-order diffracted light and the + 1st-order diffracted light, and the 0th-order diffracted light and the −1st-order diffracted light overlap each other by appropriately selecting the diffraction grating pitch p with respect to the light collection angle φ and the wavelength λ.
[0017]
The overlapped light has a first interference image observation system 6 and a second interference image observation system 7 whose centers are substantially located on the first plane, and a first interference image whose center is substantially located on the second plane. 3 interference image observation system 8 and second interference image observation system 9.
[0018]
FIG. 3 shows the configuration of these interference image observation systems. 10 is an objective lens, 11 is an imaging lens, and 12 is a CCD camera. The light diffracted through the diffraction grating 5 forms an interference fringe on the pupil plane of the objective lens 10, and this interference fringe is imaged on the image receiving element of the CCD camera 12 by the imaging lens 11. Then, the processing device 13 detects aberration based on the received interference fringes. The detected aberration is one of the aberrations having sufficient sensitivity to the decentering of the second lens 4, for example, astigmatism or coma.
[0019]
A generally known fringe scanning method is preferably used for detecting the aberration. The diffraction grating 5 is moved in a direction orthogonal to the grating direction of the diffraction grating 5 or a direction including the orthogonal component by using a piezo-type moving mechanism (fine movement stage) 14 using a piezoelectric element, for example, as shown in FIG. When the grating moves in the B or C direction, the light intensity in the interference region changes in a sine wave shape. In this case, aberration detection with high accuracy can be performed based on the phase difference without being affected by unevenness of the light intensity. Then, the processing device 13 moves (finely moves) the diffraction grating 5 by the piezo-type moving mechanism 14, obtains the phase of the light intensity at a plurality of points on a certain reference line set in the interference region, and calculates the phase difference between them. The corresponding aberration is obtained.
[0020]
Next, a method for adjusting the position of the second lens 4 with respect to the optical axis will be described with reference to a process flow shown in FIG.
[0021]
First, the first lens 1 fixed to the lens barrel is fixed by the lens barrel holder 15. Next, the second lens 4 is held by the lens holder 16.
[0022]
The light source 2 is caused to emit light at the position where the second lens 4 is held and at the first measurement point, and the processing device 13 detects the aberration. Then, the second lens 4 is moved by a predetermined amount along the straight line Y = X by the adjusting device 17 and moved to the second measuring point, and the processing device 13 detects the aberration again. Here, FIG. 5 shows changes in the two aberration amounts measured by the first interference image observation system 6 and the second interference image observation system 7 when the second lens 4 is moved in the X direction. Changes in the two aberration amounts measured by the image observation system 8 and the fourth interference image observation system 9 are shown in FIG.
[0023]
The amount of aberration by the third interference image observation system 8 and the fourth interference image observation system 9 on the YZ plane hardly changes with the movement of the second lens 4 in the X direction, whereas the amount of aberration on the XZ plane changes. One of the aberrations caused by the first interference image observation system 6 and the second interference image observation system 7 increases, and the other decreases. The intersection is an aberration symmetric position where the two aberrations are equal, and the optical axis of the first lens 1 and the optical axis of the second lens 4 coincide with each other in the X direction.
[0024]
Similarly, for the movement of the second lens 4 in the Y direction, the amount of aberration by the third interference image observation system 8 and the fourth interference image observation system 9 on the YZ plane varies as shown in FIG. While the aberration symmetry position is obtained, the amount of aberration by the first interference image observation system 6 and the second interference image observation system 7 on the XZ plane hardly changes.
[0025]
Accordingly, when the second lens 4 is moved along the straight line Y = X by the adjusting device 17 and the aberration is measured, a graph as shown in FIG. 5 can be drawn in the X and Y directions, and the intersections where the aberrations are symmetrical are obtained. Can do. Normally, in the case of a lens or a lens group used in a camera, the MTF is greatly deteriorated with respect to light having a large angle of view, which affects the characteristics. In this adjustment system, since the light has an angle of ψ1 or ψ2 ° with respect to the optical axis, the amount of change in aberration is larger than that for light on the axis (incident angle 0 °), and the intersection is highly accurate. Can be detected.
[0026]
In a lens used in a certain digital camera, the calculation result of the change in cross-direction astigmatism when the second lens 4 is decentered from the optical axis on a plane with the optical axis as a normal line is expressed as axial light. FIG. 7 shows the case of (incident angle 0 degree), and FIG. 8 shows the case of off-axis light (incident angle 12 degrees). The amount of aberration change of the second lens 4 with respect to the decenter of 1 μm is not more than 0.1 mλ for the on-axis light, but is 5.5 mλ for the off-axis light. It can be seen that highly accurate position detection can be performed.
[0027]
This intersection position is sent to the control device 18. Then, the control device 18 drives the adjustment device 17 based on this position, and moves the second lens 4 on the XY plane to adjust the position of the lens 4.
[0028]
Although the aberration measurement for calculating the aberration symmetry position is performed at two points on the straight line Y = X by moving the second lens 4, the aberration measurement is performed at two or more points on Y = X. Needless to say, the accuracy is improved.
[0029]
As described above, according to the first embodiment, in order to adjust the second lens with respect to the first lens, the optical axis of the first lens is used as a reference optical axis. (B) a step of splitting the incident light into a first light that is not subjected to lateral displacement by the quartz plate and a second light that is subjected to lateral displacement. And (c) a step of reflecting the branched two light by a half mirror and entering the second lens, (d) a step of reflecting the incident light on the surface of the second lens, and (e) the reflected light. And (f) condensing the branched light onto the line of the line sensor with a cylindrical lens, and (g) detecting the position of the second lens reflected light with the line sensor. And (h) from the detection position, the second lens The center adjustment and tilt amount are calculated, and (g) the second lens is adjusted based on the calculated amount. Detection and adjustment can be performed with high accuracy.
[0030]
(Second Embodiment)
FIG. 9 shows a combined lens adjustment system according to the second embodiment of the present invention. In FIG. 9, those having the same functions as those in FIG. 1 have the same operations, and are described with the same reference numerals. Omitted.
[0031]
Reference numeral 19 denotes an adjustment device having a decenter (XY) adjustment and a tilt (θxθy) adjustment function, and is driven based on a command from the control device 16. A processing device 20 detects two types of aberration from the interference fringes.
[0032]
Next, a lens adjustment method according to this embodiment will be described. The flow is almost the same as in the first embodiment, except that the tilt amount is calculated and adjusted in addition to the number of aberrations to be detected and the decenter amount of the second lens 4.
[0033]
In the present embodiment, the processing device 20 treats two aberrations having sufficient sensitivity to decentering of the second lens 4 and having a difference in sensitivity to tilt, for example, astigmatism and coma. Detect at. When the second lens 4 is moved by a predetermined amount along the straight line Y = X and the two aberrations are detected at the first measurement point and the second measurement point, a graph as shown in FIG. I can draw. When the second lens 4 has a tilt, the coma aberration has a higher sensitivity to the tilt than the astigmatism, and therefore, the astigmatism and the coma aberration cause a shift at the intersection (aberration symmetry position) of the graph.
[0034]
FIG. 11 shows the intersection position of astigmatism and coma aberration with respect to the tilt amount of the second lens 4 and the shift amount thereof. Since the amount of misalignment of the intersection of astigmatism and coma is a fixed value with respect to the tilt amount of the second lens 4, the tilt amount of the second lens 4 can be calculated by measuring this misalignment amount. Can do. At the same time, the intersection position (= optical axis) when the tilt amount is 0 can be calculated. Based on the tilt amount and the center position, the control device 18 drives the adjustment device 19 to perform decentering and tilt adjustment of the second lens 4.
[0035]
As described above, in the first embodiment, only the decenter amount of the lens is detected / adjusted, whereas according to the second embodiment, the lens has sensitivity to the decenter of the lens and is tilted. By measuring two aberrations having different sensitivities, for example, astigmatism and coma aberration, the decenter amount and tilt amount of the lens can be independently detected and adjusted with high accuracy.
[0036]
(Third embodiment)
FIG. 12 shows a lens adjustment system according to the third embodiment of the present invention.
[0037]
In FIG. 12, reference numeral 31 denotes a lens barrel, and 32 denotes a first lens fixed to the lens barrel. The optical axis of the first lens 32 is an optical axis (Z axis) of the lens adjustment system.
[0038]
In this lens adjustment system, light emitted from a light source 33 that emits circularly polarized light is laterally transmitted by a crystal plate 34 that is arranged so that its optical axis forms an angle of 45 degrees with the light beam on a plane including the light beam. The light is branched into first light that is not subjected to displacement and second light that is subjected to lateral displacement d. The branched two light beams are reflected by the half mirror 35 and are incident on the second lens 36 that is an adjusted lens. The light source 33, the crystal plate 34, and the half mirror 35 are positioned so that the first light incident on the second lens 36 coincides with the optical axis.
[0039]
The light reflected by the surface of the second lens 36 passes through the half mirror 35 and enters the PBS 37. The PBS 37 is positioned so that its reflection surface is parallel to the Y axis and 45 ° to the optical axis (Z axis), the component whose polarization direction is parallel to the X axis is transmitted, and the component parallel to the Y axis is reflect. The transmitted light of the PBS 37 is detected by a first line sensor 38 whose center is the optical axis and whose line direction is parallel to the Y axis.
[0040]
The reflected light of the PBS 37 is detected by a second line sensor 39 centered on the light beam when the light on the optical axis is reflected by the PBS 37 and the line direction is parallel to the Z axis. Between the PBS 37 and the first line sensor 38, there is a first cylindrical lens 40 that collects the light spread in the X-axis direction, and the PBS 37 transmitted light shifted in the X-axis direction is transmitted on the first line sensor 38. To collect light. Similarly, between the PBS 37 and the second line sensor 39, there is a second cylindrical lens 41 that collects light that has spread in the Z-axis direction, and PBS 37 reflected light that is shifted in the Z-axis direction is reflected on the second line. The light is condensed on the sensor 39. In the present embodiment, the detection of the position of light is performed at a high speed because the two light beams are separated and separated by separate line sensors.
[0041]
Next, a method for adjusting the position of the second lens 36 with respect to the optical axis will be described with reference to a process flow shown in FIG.
[0042]
First, the first lens 32 fixed to the lens barrel is fixed by the lens barrel holder 42. Next, the second lens 36 is held by the lens holder 43.
[0043]
Here, when the light source 33 is caused to emit light and the crystal plate 34 is rotated around the light beam by the rotation mechanism 44, the second light rotates around the first light. Accordingly, two lights, light on the optical axis (first light) and light rotating around the optical axis (second light), enter the second lens 36. When the second lens 36 is not decentered and tilted, the position of the reflected light from the second lens 36 is one point on the optical axis that is the reflected light of the first light and the reflected light of the second light. It becomes a circle with a certain radius centered on a certain optical axis.
[0044]
When the second lens 36 is decentered and tilted, the reflection point position C1 of the first light is shifted from the optical axis, the locus of the reflected light of the second light becomes an ellipse, and the center C2 is also from the optical axis. Shift. By observing the transmitted light of the PBS 37 with the first line sensor 38, the Y coordinate of C 1 and the ellipse diameter and the axial direction of the ellipse drawn by the second light are detected, and the second line sensor 39 By observing the reflected light of the PBS 37, the X coordinate of C1 and the ellipse diameter and the axial direction of the ellipse drawn by the second light are detected.
[0045]
The detected C1, C2, and elliptical shape values are sent to the processing device 45, and compared with the calculated values obtained from the surface shape of the second lens 36, the tilt amount and the decenter amount of the second lens 36. Can be calculated. The calculation result is sent to the control device 46, and the adjustment device 47 is driven based on the calculation result to adjust the second lens 36.
[0046]
In addition, by inserting a cylindrical lens condensing in a direction perpendicular to a direction in which each cylindrical lens condenses between the PBS 27 and the first first cylindrical lens 40 and the second cylindrical lens 41, Needless to say, the light is collected and the position detection system is improved.
[0047]
As described above, according to the third embodiment, the lens is irradiated with two lights branched by the rotating quartz plate, and the reflected light position is observed and analyzed by the two line sensors. The lens tilt / decenter amount can be detected independently and at high speed for adjustment.
[0048]
As described above, according to the present invention, there is provided a method for adjusting the position of the second lens with respect to the first lens , wherein (a) the collimated light includes the optical axis of the first lens. A first light having an inclination of + ψ1 degree with respect to the optical axis on a plane of the first light, a second light having an inclination of −ψ1 degree with respect to the optical axis, and orthogonal to the first plane and the a third light having an inclination of + .psi.2 degrees to the optical axis on a second plane including the optical axis, is branched into the fourth light having an inclination of -ψ2 degrees to the optical axis, the first A step of condensing each of the first to fourth lights with the first and second lenses, (b) a step of diffracting and interfering with the collected four lights with a diffraction grating, and (c) the above Receiving four interference images formed from the four interfering lights, and (d) each of the four received interference images. Detecting an aberration having sensitivity to decentering of the second lens, and (e) changing the position of the second lens on a plane having the optical axis as a normal line, and then Detecting an aberration having sensitivity with respect to a decenter of the lens, (f) determining a relationship of an aberration change with respect to a position change of the second lens from the detection result, and (g) calculating the relationship from the determined relationship. Calculating a position where the aberration amount for the first light and the aberration amount for the second light are equal, and a position where the aberration amount for the third light and the aberration amount for the fourth light are equal; ) By adjusting the second lens to the calculated position, it is possible to detect and adjust the decenter amount with high accuracy even for a lens having a small NA. .
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a first embodiment of the present invention. FIG. 2 is a diagram showing an example of a diffraction grating shape in the first embodiment. FIG. 3 is an interference image observation system in the first embodiment. FIG. 4 is a diagram showing an adjustment flow in the first embodiment. FIG. 5 is a diagram showing an aberration fluctuation amount of the observation system on the XZ plane with respect to a lens X direction position fluctuation in the first embodiment. FIG. 6 is a diagram showing an aberration variation amount of the observation system on the YZ plane with respect to a lens X-direction position variation in the first embodiment. FIG. FIG. 8 is a diagram showing an example of a calculation result of a variation amount of astigmatism in a cross direction with respect to the angle. FIG. FIG. 9 is a schematic diagram of the second embodiment of the present invention. FIG. 11 is a diagram showing aberration fluctuation amount with respect to lens position fluctuation when there is a tilt in the second embodiment. FIG. 11 is a diagram showing positional deviation amounts of astigmatism and coma aberration with respect to the lens tilt amount in the second embodiment. 12 is a schematic diagram of a third embodiment of the present invention. FIG. 13 is a diagram showing an adjustment flow in the third embodiment. FIG. 14 is a schematic diagram showing an example of a conventional lens adjustment system. Diagram showing diffraction by conventional diffraction grating 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 1st lens 2 Light source 3 Optical branching device 4 2nd lens 5 Diffraction grating 6 1st interference image observation system 7 2nd interference image observation system 8 3rd interference image observation system 9 4th interference image observation System 13 Processing device 14 for detecting one aberration 14 Moving mechanism 15 Lens holder 16 Lens holder 17 Adjustment device 18 having parallel moving mechanism Control device

Claims

A method for adjusting the position of a second lens relative to a first lens, comprising:
(A) The collimated light is divided into first light having an inclination of + ψ1 degree with respect to the optical axis on a first plane including the optical axis of the first lens, and −ψ1 degree with respect to the optical axis. A second light having an inclination of λ, a third light having an inclination of + ψ2 degrees with respect to the optical axis on a second plane orthogonal to the first plane and including the optical axis, and the optical axis a step of respectively condensing the fourth is branched into the light, from said first said fourth light first and second lens having a slope of -ψ2 degrees with respect to,
(B) diffracting each of the collected four lights with a diffraction grating and causing them to interfere with each other;
(C) receiving four interference images formed from the four interfering lights;
(D) detecting an aberration having sensitivity to the decenter of the second lens from the received four interference images;
(E) detecting an aberration having sensitivity to decentering of the second lens after changing the position of the second lens on a plane having the optical axis as a normal line;
(F) obtaining a relationship of aberration change with respect to position change of the second lens from the detection result;
(G) From the obtained relationship, the position where the aberration amount for the first light and the aberration amount for the second light are equal, and the aberration amount for the third light and the aberration amount for the fourth light are equal. Calculating a position;
(H) adjusting the second lens to the calculated position;
A lens adjustment method comprising:

An apparatus for adjusting the position of a second lens with respect to a first lens,
A light source that emits collimated light;
Collimated light is divided into first and second light having an inclination of ± ψ1 degrees with respect to the optical axis on a first plane including the optical axis of the light, and orthogonal to the first plane and the a device for splitting the third and fourth light having an inclination of ± .psi.2 degrees to the optical axis on a second plane including the optical axis,
An adjusting device for adjusting the position of the second lens on a plane having the optical axis as a normal line;
A diffraction grating that diffracts and interferes with the light collected by the first and second lenses;
An interference image observation system for observing four interference images formed by the diffraction grating;
A processing device that processes the four interference images and detects an aberration having sensitivity to decentering of the second lens;
From the detected aberration, the relationship of the aberration change with respect to the position change of the second lens is obtained, and from the obtained relationship, the aberration amount for the first light and the aberration amount for the second light are equal and the third A control device that calculates an adjustment amount to a position where the aberration amount with respect to the fourth light and the aberration amount with respect to the fourth light are equal, and controls the adjustment device based on the calculated adjustment amount;
A lens adjusting device comprising:

A method for adjusting the position of a second lens relative to a first lens, comprising:
(A) The collimated light is divided into first light having an inclination of + ψ1 degree with respect to the optical axis on a first plane including the optical axis of the first lens, and −ψ1 degree with respect to the optical axis. A second light having an inclination of λ, a third light having an inclination of + ψ2 degrees with respect to the optical axis on a second plane orthogonal to the first plane and including the optical axis, and the optical axis a fourth light having an inclination of -ψ2 degrees with respect, to binary Toki, a step of respectively focusing in the from first said fourth light first and second lenses,
(B) diffracting each of the collected four lights with a diffraction grating and causing them to interfere with each other;
(C) receiving four interference images formed from the four interfering lights;
(D) detecting first and second aberrations having sensitivity to decentering of the second lens from the received four interference images,
(E) a step of detecting first and second aberrations having sensitivity to decentering of the second lens after changing the position of the second lens on a plane having the optical axis as a normal line; When,
(F) obtaining a relationship of aberration change with respect to position change of the second lens from the detection result;
(G) From the obtained relationship, the position where the aberration amount for the first light and the aberration amount for the second light are equal, and the aberration amount for the third light and the aberration amount for the fourth light are equal. Calculating a position for each of the first and second aberrations, respectively;
(H) calculating a decenter amount and a tilt amount of the second lens from the calculated shift amount of the first aberration position and the second aberration position;
(I) adjusting the second lens based on the calculated decenter amount and tilt amount;
A lens adjustment method comprising:

An apparatus for adjusting the position of a second lens with respect to a first lens,
A light source that emits collimated light;
Collimated light is divided into first and second light having an inclination of ± ψ1 degrees with respect to the optical axis on a first plane including the optical axis of the light, and orthogonal to the first plane and the a device for splitting the third and fourth light having an inclination of ± .psi.2 degrees to the optical axis on a second plane including the optical axis,
An adjusting device that adjusts the position of the second lens on a plane that is normal to the optical axis in a biaxial direction orthogonal to the rotation direction and the rotational direction around the two axes;
A diffraction grating that diffracts and interferes with the light collected by the first and second lenses;
An interference image observation system for observing four interference images formed by the diffraction grating;
A processing device that processes the four interference images and detects at least two aberrations having sensitivity to decentering of the second lens;
From the two detected aberrations, the relationship of the aberration change with respect to the position change of the second lens is obtained, and the aberration amount for the first light is equal to the aberration amount for the second light from the obtained relationship. Then, a position where the aberration amount for the third light and the aberration amount for the fourth light are equal is calculated, and the decenter amount and tilt amount of the second lens are calculated from the calculated shift amount of the two aberration positions. A control device that calculates, calculates an adjustment amount based on the calculated decenter amount and tilt amount, and controls the adjustment device based on the calculated adjustment amount;
A lens adjusting device comprising: